A commission charged with examining the scope and depth of the attack's health effects reviewed more than 100 scientific articles published since 2001 and found that new asthma levels among residents and rescue workers were two to three times higher than the national estimates.

The report by the World Trade Center Medical Working Group, issued in advance of the September 11 anniversary, also found that two to three years after the attack, symptoms of post-traumatic stress disorder remained elevated among rescue and recovery workers and residents of lower Manhattan.